Plastic microbeads are small synthetic polymer particles, typically smaller than 1 mm in diameter, that were added to a variety of skin care products as gentle abrasive agents; they have also been used in a variety of household and industrial cleaning products. A number of polymers have been commonly added to skin care products, with the most common being polyethylene. (See, e.g., Environment and Climate Change Canada, Microbeads—A Science Summary (July 2015); the disclosure of which is incorporated herein by reference in its entirety.) Within the last several years, there has been growing awareness and concern about these synthetic microbeads as a significant source of microplastic pollution to terrestrial and marine ecosystems (do Sul and Costa, Enviro. Pollution (2014); Eriksen et al., Marine Pollution Bulletin (2013); Mason et al., Enviro. Pollution (2016); the disclosures of which are hereby incorporated by reference in their entirety.) Recent and planned legislation in the United States, Canada, and Europe has sought to curtail and/or ban the use of microbeads in cosmetic products. (MacDonald, Environmental Defence Press Release, (Jun. 29, 2016); H.R. 1321, 114th Cong. (2016); the disclosures of which are hereby incorporated by reference in their entirety.) Even prior to these proposed and planned microbead bans taking effect, some companies have replaced plastic abrasives with alternative particles, including walnut shells, silica gel beads, jojoba wax beads, and other waxes. Walnut shells are the subject of an ongoing lawsuit alleging that the angularity and roughness of this material causes “micro-tears” in skin. (Browning v. Unilever US, Inc., No. 8:2016cv02210 (C.D. Calif. Filed Dec. 16, 2016); the disclosure of which is incorporated herein by reference in its entirety.) The low density and hydrophobicity of waxes can be problematic for even distribution within various cosmetic materials. While there has not been a comparable public demand for the banning of microplastic abrasives in cleaning products, this too may change and some of the non-plastic particles being used in skincare products (e.g., waxes and silica gel) are likely too soft to be useful alternatives to plastic for these applications. There is, therefore, a clear need for a microabrasive material that is small, microscopically smooth, harder and denser than wax or amorphous silica, and environmentally benign.